Kit for the determination and diagnosis of non-goodpasture glomerulonephritis

ABSTRACT

Purified glomerular proteoglycans are used as a basis for a diagnostic test for glomerulonephritis in humans involving an immunological reaction between the purified proteoglycans and patient area. A new method for purification of glomeruli proteoglycan antigens is described using guanidine extraction.

This invention was made with government support under PHSSK08AM00981from the National Institutes of Health. Therefore, the government hascertain rights in this invention.

This is a divisional of application Ser. No. 618,500, filed June 8,1984, and now issued as U.S. Pat. No. 4,849,339.

This invention relates to a diagnostic method for glomerulonephritis.

SUMMARY

Purified glomerular proteoglycan antigens serve as the basis for animmunological test in patients with various forms of acute and chronicrenal disease.

DESCRIPTION

Studies of humoral autoimmunity in glomerulonephritis (GN) have revealedthe importance of antibodies directed against a noncollagenousglomerular basement membrane (GBM) antigen, termed Goodpasture'santigen, in patients with rapidly progressive glomerulonephritis(Wilson, C. B., et al. (1973) Kid. Int. 3:74-89.). These antibodies arefound in only about 1% of all patients with glomerular disease. Oneprotein presumably representing Goodpasture's antigen has been isolatedwith an apparent unit molecular weight of 26,000 (Weislander, J., et al.(1984) Proc. Nat. Acad. Sci. 81:1544-1548). A diagnostic based on a moreprevalent antigen or antigenic determinant in GN would be more useful.Evidence suggesting that humoral autoimmunity may be present in abroader spectrum of patients comes from earlier studies (Liu, C.T., etal. (1958) J. Immunol. 81:492-498; Kramer, N.C., et al. (1961) Am. J.Med. 30:39-45; Lange, K., et al. (1949) J. Clin. Invest. 28:50-55;Chudomel, V.,e t al. (1961) Lancet ii: 965-967) in which autoantibodiesto crude kidney antigen were found in patients with acute and chronicGN. Other glomerular antigens may be the focus of glomerularautoimmunity (Weislander, J., et al. (1983) Kid. Int. 23:855-861;Foidart, J.B., et al. (1980) Kid. Int. 18:136; Wick, G., et al. (1980)Clin. Exp. Immunol. 39:733-740).

Antibodies to GBM antigens solubilized by guanidine, pepsin orcollagenase digestion were found in patients with systemic lupus GN, IgAnephropathy, and polyarteristis nodosa (Weislander, J. et al. (1983)Supra), and the presence of autoantibodies to laminin and type IVcollagen were noted in patients with Goodpasture's syndrome (Foidart,J.B., et al. (1980) Supra), although others have not found anti-lamininor anti-type IV collagen reactivity (Wick, G., et al. (1980) Supra).

Cellular autoimmunity to glomerular antigens has been shown using avariety of cellular assays in a spectrum of histologic types of humanGN, including patients without clinical or histologic features ofGoodpasture's disease (Fillit, H.M., et al. (1982) Am. J. Path.109:227-243; Bendixen, G., (1968) Acta. Med. Scand. 184:99-103; Rocklin,R., et al. (1970) New Engl. J. Med. 248:498-501; Dardenne, M., et al.(1970) Lancet i:126-128; Mahieu, P., et al. (1972) Am. J. Med.53:185-192; Macanovic, M., et al. (1972) Lancet ii:207-210; Mallick, N.,et al. (1972) Lancet i:507-509; Fillit, H.M., et al. (1978) N. Engl. J.Med. 298:861-867; Matsumoto, K., et al. (1978) Nephron 21:192-200;Matsumoto, K., et al. (1982) Nephron 30:205-209). Cellular reactivity tocrude GBM antigens has been found in patients with various forms ofchronic GN (Fillit, H.M., et al. (1978) Supra) who did not haveantibodies against Goodpasture's antigen (Fillit, H. M., et al. (1978)Kid. Int. 14:710). Whether cellular autoimmunity occurs to antigens towhich no humoral immune response is made, or to antigens which have notbeen identified for humoral testing, remains unknown. Autoimmunity to avariety of glomerular antigens may occur in a spectrum of histologictypes of acute and chronic GN.

We have isolated soluble anionic glomerular antigens and demonstratedhumoral autoimmunity to these antigens in patients with various forms ofacute and chronic renal disease in the present invention. Biochemicalcharacterization of these anionic antigens indicates that they areproteoglycans. The glycosaminoglycan chains, specifically heparansulfate, appear to be the primary site of immune reactivity. Purifiedhuman umbilical cord hyaluronate and purified streptococcal hyaluronatealso inhibit the observed reactivity to the proteoglycan material,albeit to a lesser degree, indicating cross-reactivity in the immuneresponse to glomerular heparan sulfate, tissue hyaluronate, andstreptococcal hyaluronate in patients with acute poststreptococcalglomerulonephritis (APSGN). A second immunoreactive site of theglomerular proteoglycan appears to be related to N-acetylgalactosamine.Glomerular autoimmunity may also be directed to the protein portion ofthe proteoglycan.

Subjects: Patients with chronic renal disease were seen in TheRockefeller University Clinic or at The New York Hospital. Only patientswith chronic renal disease who had renal biopsies as part of theirmedical evaluation were entered into our study. Patients with acutepoststreptococcal GN (APSGN) and chronic poststreptococcal GN (CPSGN)were seen in San Fernando, Trinidad, as part of a collaborative effortwith Dr. Theo Poon-King. All of these patients had extensive clinicalstudies, including antistreptolysin 0 titers and streptococcal cultures,to document the presence of APSGN. Dr. Luis Tapia provided sera frompatients on hemodialysis.

DEAE-Sepharose CL-6B and Sepharose CL-4B were obtained from Pharmacia.Chondroitinase ABC was purchased from Miles Laboratories.DEAE-Cellulose, pepstatin A, benzamidine-HCl, 6-aminohexanoic acid,guanidine-HCl (Grade 1), phenylmethylsulfonyl flouride,N-ethylmaleimide, diatomaceous earth (grade I), were purchased fromSigma. Papain (twice crystallized) was a product of WorthingonBiochemicals. Urea (Fisher, certified ACS) as an 8M solution was passedthrough a Fisher high capacity deionizing cartridge shortly before use.Purified glycosaminoglycans (GAG's) were obtained from Allen Horowitz,University of Chicago, Chicago, Illinois. These includedchondroitin-4-sulfate and chondroitin-6-sulfate (S. platorhyncus),hyaluronate (human umbilical cord), dermatan sulfate (hog mucosa),heparin (beef lung), and heparan sulfate (beef lung). Group Astreptococcal hyaluronate and group A, A variant, and C carbohydrateswere obtained from Dr. Maclyn McCarty. N-acetylglucosamine,N-acetylmannosamine, N-acetylgalactosamine and D-glucuronic acid wereobtained from Sigma.

Isolation of glomerular proteoglycans from whole glomeruli byguanidine-HCl extraction: Glomeruli were isolated from fresh bovine andhuman kidneys by a sieving method (Misra, R.P., (1972) Am. J. Clin.Path. 58:135-140). The frozen glomeruli were thawed, and centrifuged at2,500 rpm for ten minutes. The pellet volume was measured and the pelletdiluted 1:100 (v/v) in distilled water containing protease inhibitors(0.1M 6-aminohexanoic acid, 0.005M benzamidine, 0.01M EDTA), stirredmagnetically for three hours at 4C, and centrifuged at 12,100 g for tenminutes (Table 1). The pellet was resuspended in 4M guanidine HCl in0.05M sodium acetate buffer, pH 5.8, with protease inhibitors asdescribed above, stirred magnetically for 48 hours at 4C, andcentrifuged as above. A second extraction in the same solvent wasperformed for 18 hours. The combined supernatants were dialyzed (inSpectrophor 3 membrane tubing) against three changes of ten volumes ofdeionized 7M urea with 0.01M EDTA, 0.05M Tris HCl buffer, pH 6.5.

A DEAE-Sepharose CL-6B column was prepared, with a bed volume of 80 ml,and washed with four bed volumes of the above urea buffer at 4C. Theextract was filtered through diatomaceous earth to remove insolublematerial, and the cake was washed thoroughly with the 7M ure buffer. Thefiltrate was loaded on to the column and eluted stepwise with threecolumn volumes of increasing concentrations of NaCl in 7M urea buffer(from 0.0M to 1.0M NaCl with 0.1M NaCl increments). Each eluate wasextensively dialyzed against distilled water and lyophilized. Thematerial eluted with 0.4M, 0.5M, and 0.6M NaCl was redissolved in 0.5Msodium acetate, pH 5.8, and was finally rechromatographed on SepharoseCL-4B (0.78×110 cm) in 0.5M sodium acetate buffer, pH 5.8. Each elutionwas extensively dialyzed against distilled water and lyophilized.

Preparation of bovine anionic glomerular basement membrane (GBM)antigens: Glomeruli were prepared from fresh bovine kidneys by gradedsieving (Misra, R.P., (1972) Supra). The isolated glomeruli were frozenat -70C in 0.15M NaCl with 0.02% azide until further use. For theisolation of GBM, a modification of a previous method (Meezan, E., etal. (1975) Life Sci. 17:1721-1732) was used. The glomeruli were thawedand spun at 2000 g for ten minutes in an IEC centrifuge. Pelletedglomeruli were added to distilled water containing 0.02% azide (100:1),stirred magnetically for 2 hours at 4° C, and then centrifuged at 12,100g for twenty minutes at 4° C. The supernatent was removed, placed in aSpectrophor dialysis membrane (molecular weight cutoff of 3500),dialyzed against distilled water, and lyophilized. Sodium deoxycholate(4% in 0.02% azide) was added to the pellet (40:1, v/v) and stirred foreighteen hours at 4° C. After centrifugation at 12,100 g for twentyminutes, the supernatent was removed and 0.15 M phosphate

buffered saline (PBS) containing 3mM MgC1₂ was added to the pellet(40:1) v/v) gradually with stirring. DNAase (Sigma, D4638) (1 mg /100 mlPBS) was added, the suspension was stirred magnetically at 4° C. forfour hours, centrifuged at 23,000 g for twenty minutes, and thesupernatent removed. For extraction of soluble GBM antigens, amodification of a previous method was employed (Kefalides, N.A., (1972)Conn. Tiss. Res. 1:3-13). Urea (8M, Aristar) in 0.15 M KP04 pH 5.5 wasadded to the GBM pellet (50:1, v/v). The GBM-urea mixture was suspendedusing a waterbath sonicator at room temperature for 15 seconds, and thematerial gently stirred at 37° C. for eighteen hours. The urea extractwas centrifuged at 12,100 g for twenty minutes, and the supernatant wasstored at 4° C. Two further urea extractions were performed, and allsupernatants were dialyzed against five change of eighteen liters ofdistilled water (in a Spectrophor 3 dialysis bag with a molecular weightcutoff of 3,500) and subsequently lyophilized. The three extracts werecombined, and 300 mg was used for DEAE-Cellulose chromatography.

DEAE-Cellulose (Sigma 8382) was equilibrated in 0.005M sodium acetate pH5.5 containing 8M urea and was poured into a column 2.7 cm×15 cm, andwashed with 100 ml of urea-acetate buffer. The urea extracted material(300 mg) was added to 30 ml of urea-acetate buffer, briefly sonicated ina probe sonicator (Ultrasonics, Plainview, N.Y.) for five seconds toobtain a suspension, and then stirred overnight at 37° C. The suspensionwas centrifuged at 12,100 g for ten minutes, and the supernatant wasloaded on to the DEAE column. A stepwise elution employing three columnvolumes each of urea-acetate buffer, 0.1M NaCl, 0.3M NaCl, 0.6M NaCl and1M NaCl in urea-acetate buffer was performed. Fractions (10 ml) werecollected, and monitored with a Beckman spectrophotometer at 280 nm.Each step was dialyzed extensively against distilled water (in aSpectrophor 3 membrane tubing), and lyophilized. The material used asantigen was the 0.6M NaCl elution (abbreviated: 0.6M-DE-urea-GBM).

SDS Polyacrylamide gel electrophoresis: The various samples wereelectrophoresed on SDS polyacrylamide slab gel electrohporesis(SDS-PAGE) using a modification of standard methods (Laemmli, U.K.,(1970) Nature 227:680-685). Briefly, varying amounts of lyophilizedsample were placed in SDS sample buffer without beta-mercaptoethanol.The samples were warmed to 37° C. and dissolved in a waterbath sonicatorfor ten seconds. A 4-15% gradient gel (0.1 cm. in thickness, 10 cm. inheight) with a 3% stacking gel was employed. Electrophoresis was carriedout for approximately one hour with 60 ma current. Gels were stainedwith 0.1% Coomassie brilliant blue R250 in 25% isopropanol-10% aceticacid in distilled water and stained in isopropanol-acetic acid indistilled water. Some gels were stained with Alcian blue by fixing thegels in 0.lN HCl or or 10% acetic acid, followed by the addition of 0.1%Alcian blue in 10% acetic acid containing 0.05M MgCl₂ for approximatelytwo hours. Finally, the gels were destained in 0.6N HCl.

Isoelectric focusing: Isoelectric focusing was performed according todescribed methods (Isoelectric focusing, Pharmacia Fine Chemicals,Ljungforetagen AB, Orebro, Sweden, 1982) with an LKB multiphorapparatus. Agarose (1%) in sorbitol was prepared at 100° C. and pouredonto Gelbond (LKB). The buffers for the electrodes were 0.1M H and 0.2Mhistidine. Ampholines 2.5-4.0 and 4.0-6.0 (LKB) were employed at 2%.Focusing was performed at 600 volts for three hours at 5 watts. The gelswere fixed in fixing solution (containing 17.3 grams of sulfosalisylicacid, 57.5 gms trichloroacetic acid, and 150 ml methanol, brought to 500cc total volume with distilled water), and washed twice in ethanol forten minutes. Finally, the gel was dried by pressing with filter paperusing one kilogram for thirty minutes, dried with mild heat, and stainedwith 0.1% Alcian blue and 0.05% Coomassie Blue R 250 in fixing buffer,and destained in the same buffer.

Immunoblotting: Immunoblotting was performed according to the method ofBlake et al ((1984) Anal. Biochem. 136:175-179). Briefly, SDS-PAGE wasperformed as described above. After electrophoresis, the gels werebriefly washed in methanol blotting buffer, placed on nitrocellulosepaper (Schleicher and Scheull) in a sandwich of Whatman chromatographypaper between two sponges, and placed in a blotting apparatus. Blottingwas performed with 1.0 amp of current at constant (1 volt) voltage forone hour. The gels were removed, and the nitrocellulose was cut in 1 cm.strips and placed in 0.1M phosphate buffered saline, pH 7.4, containing0.5% Tween 20 (PBST). The paper was washed in PBST for two washes of 30minutes each to block nonspecific binding sites. Serum samples wereadded at varying dilutions in PBST overnight. The paper was then washedthree times for five minutes each in PBST and an alkaline phosphataseconjugated goat anti-human IgG (Sigma) was added at a 1:500 dilution inPBST for four hours. The paper was then washed in PBST for three washesof five minutes each, and then washed in PBST for three washes of fiveminutes each, and then washed in 0.1M veronal acetate buffer, pH 9.6,for five minutes. Finally, a developing reagent containing 40microliters of 2M MgCl₂ 1 ml of 0.1% nitro blue tetrazolium in veronalacetate pH 9.6, and 100 microliters of a 5mg/ml solution of 5-bromo,4-chloro indoxyl phosphate (U.S. Biochemicals) in dimethylformamide in 9ml of veronal acetate pH 9.6 was added, and the paper developed for upto one hour.

Enzyme linked immunoassay (ELISA): ELISA was performed essentiallyaccording to the methods of Engvall (Engvall, E., et al. (1972) J.Immunol. 109:129-142) with Nunc immunoplates. Various amounts of antigenwere placed in wells of the plates in 50 microliters 0.1M Tris HClbuffer, pH 9.6, containing 0.3 MgCl₂ overnight at 4° C. The plates werethen washed once with PBS containing 0.5% Brij (PBSB). Brij 35 is atrademark of Pierce Chemical Co., Rockford Illinois and is a 30%solution of polyoxyethylenelauryl ether detergent. Finally, thenonspecific sites on the plates were blocked by two further incubationswith PBSB for thirty minutes each. Serum was diluted in PBSB and 50microliters added to the plates for four hours. The plates were washedby adding 250 microliters 0.9% NaCl containing 0.5% Brij for threewashes of five minutes each. An alkaline phosphatase conjugated goatanti-human IgG (gamma chain specific) antiserum (Sigma, lot 88F 9350)was added at a dilution of 1:1000 in 50 microliters PBSB for four hours.The plates were washed in saline-Brij as above three times for fiveminutes each. Finally, a developing substrate was added. 10 mg ofnitrophenyl phosphate (Sigma) per ten ml of diethanolamine buffer(containing 97 ml diethanolamine, 1 ml of 1M MgCl₂, 1 ml of 0.1M zincacetate, 0.2 gm sodium azide, and 800 ml of distilled water, pH 9.8) wasprepared. 150 microliter of nitrophenyl phosphate diethanolaminedeveloping reagent was added, and the plates were read at 405 nm in aTitertek ELISA plate reader at intervals for up to four hours. Resultsare expressed as the titer which is the reciprocal of the dilutiongiving an absolute spectrophotometric reading of 1.0 at 405 nm.

Preparation of rabbit antisera to GBM: New Zealand white female adultrabbits were immunized with whole bovine and human GBM extracted by astandard Meezan (Meezan, E., et al. (1975) Life Sci. 17:1721-1732)extraction using deoxycholate as originally described. One mg of GBM incomplete Freund's adjuvant was injected intradermally into two rabbitsat three week intervals for a total of three injections. Serum washarvested one week after the final injection.

Chemical composition of antigenic preparations: Uronic acid was measuredby a variation of the borate/carbazole method (Bitter, T., et al. (1962)Anal. Biochem. 4:330-334). Hexosamines were quantitated on a TechniconTSM amino acid analyzer after hydrolysis in 4M HCl at 100 C for 8 hours(Kieras, F. J., (1974) J. Biol. Chem. 249:7506-7513). Protein wasmeasured by a modified Lowry procedure (Schacterle, G.R., et al. (1973)Anal. Biochem. 51:654-655) or by absorbance at 280 nm. Digestion ofproteoglycans with chondroitinase ABC (0.1 unit/mg) was done in 0.1Msodium acetate, 0.1M Tris-HCl, containing the following proteaseinhibitors: 10 mM EDTA, 10 mM N-ethylmaleimide, lmM phenylmethylsulfonylfluoride, and 0.035 mM pepstatin A, pH 7.3 at 37° C. for four hours.Digestion of proteoglycans with papain was carried out in 0.1 Mpotassium phosphate, 0.01M EDTA, 0.01M cysteine, pH 6.8, at 64° C. for18 hours. The ratio of proteoglycan to papain was 100:1. Nitrous acidtreatment of proteoglycans was carried out according to the proceduredescribed by Shively and Conrad (Shively, J., et al. (1976) Biochemistry5:3932-3942). The digests were chromatographed on Sepharose CL-4B in0.5M sodium acetate pH 5.8. Intact preparations used as controls werechromatographed under identical conditions.

The examples below serve to illustrate the invention without limitingthe scope of the invention.

The information in this specification is incorporated in a papersubmitted to the Journal of Clinical Investigation by Howard Fillit etal. entitled "Antibodies to Glomerular Proteoglycans", which paper ishereby incorporated by reference.

EXAMPLE I

Isolation of glomerular proteoglycans by guanidine-HCl extraction: Adirect 4M guanidine extraction of whole glomeruli after hypotonic lysiswas performed. The guanidine extract was fractionated by DEAE-SepharoseCL-6B chromatogrpahy, and 0.4M, 0.5M and 0.6M NaCl eluates were furtherchromatographed on Sepharose CL-4B. This scheme is summarized in FIG. 1for the bovine material (note abbreviations used in the table for theseantigens. The first number indicates the molar NaCl elution ofDEAE-Sepharose CL-6B chromatography; the second number indicates thepeak of Sepharose CL-4B chromatography. For example, 0.4M-peak IIrepresents the 0.4M NaCl eluate of DEAE-Sepharose CL-6B chromatographywhich has been further chromatographed on Sepharose CL-4B and isolatedas peak II). A similar extraction was employed with human glomeruli.However, enough human material was not available for Sepharose CL-4Bchromatography. Thus, the 0.6M NaCl eluate of DEAE-Sepharose CL-6Bchromatography (abbreviated: human-DE-0.6M) was used as antigen forthese studies.

The distribution of hexosamine-containing compounds as measured byaminosugar analysis (Kieras, F. J., (1974) J. Biol. Chem. 249:7506-7513)of the extract after DEAE Sepharose CL-6B ion -exchange chromatographyis shown in Table I. Percentage of glucosamine and galactosamine inregard to total amino sugar are determined in Table I. The glucosaminecontent of the unabsorbed and 0.1M NaCl eluates probably representsnon-charged glycoproteins and possibly non-sulfated glycosaminoglycans(free or protein bound). The major hexosamine-containing materialemerged in 0.4M, 0.5M and 0.6M NaCl eluates. A small amount ofglucosamine was present in higher salt concentrations.

The 0.4M, 0.5M and 0.6M NaCl eluates from the above CL-6B were purifiedfurther by chromatography on Sepharose CL-4B. All eluates were found tohave identical profiles. A typical profile (0.4M NaCl eluate) showsresolution of the material into three protein peaks. Peak I emerges inthe void volume (v.sub.°) of the column and contains only glucosamine.Peak II, (Kav=0.48) emerges in fractions 45-63 with a peak aboutfraction 54, contains both glucosamine and galactosamine in anapproximate ratio of 4.5 to 1 respectively. Uronic acid was also presentin peak I and peak II. Peak III eluting at approximately fraction 85(Vt) has a large amount of protein or peptides but no hexosamines. PeakIII material was not studied further ##EQU1##

EXAMPLE II

The material in peak I and II above were identified as proteoglycans bytheir susceptibility to specific enzymatic and chemical treatments. Ifthe treated material in each case was susceptible, it moved to achromatographic position on Sepharose CL-4B with a much higher Kav thanbefore treatment. All fractions were degraded by papain indicating theirprotein content. As seen in Table II, only a glucosamine-containingcomponent was present in Peak I, and it was susceptible to nitrous acidindicating the presence of a heparan sulfate proteoglycan. In peak II, aglucosamine-containing proteoglycan susceptible to nitrous acid, and agalactosamine-containing proteoglycan susceptible to chondroitinase ABCwere present, indicating a mixture of heparan sulfate and chondroitin ordermatan sulfate proteoglycans, or possibly a hybrid molecule with bothkinds of GAG. The distribution of proteoglycans in three saltconcentrations from the ion exchange column may reflect heterogeneitycaused by variable degrees of sulfation of GAG's or variable amounts ofsialic acid substitution on the oligosaccharide chains that are presentin most proteoglycans. Further characterization of the glomerularproteoglycans is in progress.

EXAMPLE III

SDS-PAGE analysis of the purified 0.4M-peakII material revealed onlyhigh molecular weight material (greater than 200,00 M.W.) whichelectrophoresed as a broad band in the gradient gel, and which wasstained more intensely by Alcian blue than Coomassie blue. This isconsistent with the fact that protein-polysaccharide complexes do notstain well with Coomassie blue, and are stained more intensely with thecationic dye, Alcian blue. Isoelectric focusing followed by stainingwith both Alcian blue and Coomassie blue in separate gels revealed thatthe pI of the isolated 0.4M-peak II fraction was between 2.94 and 3.53.Molecular weight markers are phosphorylase B relative M.W. 94,000, serumalbumin relative M.W. 67,000. These studies further demonstrated thepurity and highly anionic nature of the isolated 0.4M-peakII fraction.

SDS-PAGE analysis of the anionic GBM fractions obtained byDEAE-Cellulose ion exchange chromatography revealed that the 0.3M and0.6M elutions contained primarily high molecular weight (greater than200,000) material which failed to form a distinct band, and whichstained with both Coomassie and Alcian blue, indicating the presence ofanionic protein material. Analysis of the 0.6M elution revealed thepresence of a large amount of glucosamine, a small amount ofgalactosamine, and a high content of uronic acid, indicating that thismaterial was proteoglycan in nature.

EXAMPLE IV

Immunoblot screening studies of the DNase-1M NaCl and sodiumdeoxycholate extracts removed during the isolation of GBM revealedsubstantial quantities of high molecular weight broad banded antigenicmaterial in these fractions. An analysis of the hexosamine content ofthese extracts confirmed the presence of significant amounts of bothtotal hexosamine (both glucosamine and galactosamine) and sulfated GAGs(Table III). Nearly 80% of the total hexosamine and sulfated GAG contentof whole glomeruli was demonstrated in the sodium deoxycholateextraction. A further 4M guanidine extract of the isolated GBM containedonly 14% of the total hexosamine. Thus, major losses of glomerularhexosamine and sulfated GAGs were apparent in the deoxycholateextraction procedure for the isolation of GBM, with most of the lostmaterial appearing in the deoxycholate fraction.

EXAMPLE V

All of the purified proteoglycans obtained after Sepharose CL-4Bchromatography (FIG. 1) were tested by the ELISA. Sera from patientswith well documented APSGN, CPSGN and chronic GN (CGN) were studied.Analysis of our results thus far indicates that all of the anionic(0.4-0.6M NaCl) Sepharose CL-4B fractions give similar results usingpatient sera. Thus, although the various anionic fractions wereheterogeneous in their degree of sulfation, and therefore eluted indifferent (0.4-0.6M) molar NaCl elutions from the DEAE-Sepharose CL-6Bcolumn, they appeared antigenically similar. The 0.4M-peak II antigenwas most extensively studied and reported in detail here. An immunoblotof the purified 0.4M-peakII antigen stained with the sera from patientswith APSGN shows immunostaining of the broad banded high molecularmaterial with the APSGN patient sera, but not with the control serum orthe alkaline phosphatase conjugated anti-human IgG antiserum.

EXAMPLE VI

Using ELISA, the 0.4M-peakII antigen was titrated from 10 to 0.1micrograms per milliliter and tested with the sera from a patient withAPSGN and a control. In this experiment, a clear titration effect wasseen as the antigen concentration was changed, indicating that ELISAreactivity was directed against the antigen being used to coat theplates (Table IVa). In another representative experiment (Table IVb), aclear titration curve of reactivity is seen as the serum is diluted andthe 0.4M-peakII antigen concentration held constant, indicating that IgGin the serum being tested accounted for the observed antibody binding.Titers of the APSGN sera were higher than the CPSGN sera, while controlswere seen to contain little or no ELIS reactivity.

Both IgG and IgM antibodies to the 0.4M-PeakII antigen were found inpatient sera.

Further testing of the 0.4M-peakII antigen using patient sera showedthat 5/7 patients with APSGN, 6/9 patients with CGN, and 0/10 controlswere positive (defined as serum titer greater than 1:20) (Table V). Forthe 0.5M-peakII (Table V) similar findings were noted. In addition, whenpatients with CPSGN were tested to 0.5M-peakII, 6/11 patients were notedto be positive. Although the amount of material available for testing ofthe 0.4M-peakI and the 0.5M-peakI were limited, similar ELISA resultswith patient sera were obtained. In summary, these data indicate thepresence of antibodies in the sera of patients with various types of GNreactive with purified bovine anionic glomerular proteoglycan fractionswhich are antigenically similar, but are heterogeneous with regard totheir charge. Since the peak I fractions contained no galactosamine andrepresented purified heparan sulfate proteoglycan, immunoreactivity topurified heparan sulfate proteoglycan was demonstrated. In addition,immunoreactivity was noted to proteoglycan antigen which contained bothglucosamine and galactosamine (peak II).

EXAMPLE VII

Rabbit antisera made to both bovine and human whole GBM demonstratedreactivity to the bovine 0.4M-peakII material in ELISA studies (10microgram/ml--Table VI). As the rabbit antisera made to human GBMreacted with the bovine antigen, cross-reactivity of the bovine0.4M-peakII material with the equivalent human antigen is apparent. Inaddition, human DE-0.6M was also tested in the ELISA. Reactivity ofpatient sera was observed. A serum from a patient with APSGN reacted tothe human antigen in titers approximating that found with bovine(0.4M-peakII) antigen (titer=96). Thus, the bovine and human glomerularproteoglycan preparations demonstrate cross-reactivity on immunologictesting.

EXAMPLE VIII

Various controls were performed to specifically determine whether theELISA reactivity we noted to the purified proteoglycans was due tononspecific ionic binding of cationic IgG or due to specific binding ofantibody to antigenic sites of these anionic molecules. The inhibitionstudies were performed in both the immunoblotting and the ELISA usinghigh concentrations of NaCl (up to 1M) to inhibit binding of the0.4M-peakII material (10 microgram/ml). Essentially no inhibition wasseen (Table VII). Preincubation of the 0.4M-peakII material (62.5micrograms per milliliter) with APSGN sera (1:40) in equal volumes forone hour at room temperature and thirty minutes at 4° C. resulted inspecific inhibition of 90% of the serum reactivity to the 0.4M-peakIImaterial further demonstrating the specificity of ELISA activity.

EXAMPLE IX

Inhibition ELISA experiments with purified GAG's revealed inhibition ofAPSGN serum (1:40) reactivity to human DE-0.6M (10 microgram/ml)primarily with heparan sulfate, and not with other GAG's (Table III).The APSGN serum (1:40) was pre-incubated with various purifiedglycosaminoglycans at varying concentrations (chondroitin-4-sulfate,chondroitin-6-sulfate, heparin, bovine hyaluronate and heparan sulfate).However, further inhibition studies with the human DE-0.6M (10microgram/ml) revealed inhibition with both streptococcal and humanumbilical cord hyaluronate, although at significantly higherconcentrations of inhibitor than with heparan sulfate. Table IXillustrates an APSGN serum (1:40) pre-incubated with heparan sulfateglycosaminoglycan, bovine hyaluronate and streptococcal hyaluronate atvarying concentrations. Similar ELISA inhibition findings were notedwith the purified bovine 0.4M-peakII proteoglycan. Elisa studies weredone with 0.4M-peakII antigen at 10 microgram/ml. An APSGN sera (1:40)was preincubated with various inhibitors including dermatan sulfate,N-acetyglucosamine N-acetylgalactosamine, streptoccal hyaluronate andheparan sulfate at varying concentrations (Table X). Since hyaluronateand heparan sulfate GAG's differ primarily in their degree of sulfation,these findings would suggest that sulfation of the heparan sulfate GAGchains plays an important role in their antigenicity. In addition,cross-reactivity of heparan sulfate and hyaluronate appears to bepresent.

EXAMPLE X

Further inhibition experiments with N-acetylgalactosamine alone atconcentrations of 0.5M showed approximately 50% inhibition of APSGNserum (1:40) reactivity to 0.4M-peakII antigen, whileN-acetylglucosamine, D-glucuronic acid, and N-acetylmannosamine showedlittle inhibition at this concentration. Group C streptococcalcarbohydrate (50 mg/ml), whose immunodominant carbohydrate is a terminalN-acetylgalactosamine, also inhibited approximately 50% of APSGN serum(1:40) reactivity (Table XI). Group A (immunodominant site containingterminal N-acetylglucosamine) and A variant (immunodominant sitecontaining primarily rhamnose) streptococcal carbohydrate (50 mg/ml)showed little inhibition. The combined use of streptococcal hyaluronate(5 mg/ml) and N-acetylgalactosamine (lM, 222 mg/ml) resulted in additiveinhibition of serum reactivity (Table X). Galactosamine containing GAG'ssuch as chondroitin sulfate have thus far shown little immunoinhibitionof serum reactivity, while in one experiment dermatan sulfate showedminor inhibition at higher concentrations (5 mg/ml). Thus, these dataindicate the presence of a second antigenic site on the glomerularproteoglycan whose immunodeterminant is N-acetylgalactosamine.

EXAMPLE XI

The possibility that the serum reactivity to proteoglycan might be dueto cationic immune complexes was investigated, particularly since weknown that the APSGN sera contain high titers of immune complexes (Vande Rijn, et al. (1978) Clin. Exp. Immunol. 34:318-325). Polyethyleneglycol (PEG) precipitation of the serum was performed to remove immunecomplexes, and the supernatant of the serum run in our ELISA against thepurified 0.4M-peakII. PEG 8000 (5.4%) in 0.1M sodium borate buffer wasadded to APSGN sera (1:10) in equal volumes and incubated at 4° C. forone hour. The sera were then centrifuged at 12,000g for ten minutes. Thesupernatant was assayed by ELISA using the 0.4M-peakII material asantigen (10 micrograms/ml). The final concentration of APSGN serum was1:20. No effect on serum reactivity as judged by serum titer in theELISA, was noted after removal of the immune complexes by this method.Finally, the possibility that the serum reactivity seen might bedirected against anionic DNA contaminating the 0.4M-peakII antigen wasinvestigated. The presence of anti-single and double stranded DNAantibodies was tested by radioimmunoassay in the laboratory of Dr. HenryKunkel. No anti-DNA antibodies were detected in any of the acute andchronic patient sera which were highly reactive to the glomerularproteoglycan antigens.

EXAMPLE XII

Immunoblotting of the 0.6M eluate from DEAE-Cellulose chromatography ofthe 8M urea extracted GBM (0.6M-DE-urea-GBM) using the sera of patientswith GN showed staining of a high molecular weight broad band whichmigrated poorly into the polyacrylamide gel. All eluates obtained from aDEAE-Cellulose column were examined by immunoblotting using a patientserum with chronic proliferative GN. This serum stained broad bandedmaterial primarily in 0.4M-0.6M eluates with little staining of theunabsorbed or 0.1M-0.2M eluates. Control studies without human serademonstrated that this staining was not due to nonspecific binding ofthe alkaline phosphatase conjugated goat antihuman IgG antisera.Representative data from ELISA using 0.6M-DE-urea-GBM antigen is shownin Table XII. Fourteen of 28 chronic GN patients, but only one of 8controls, had serum antibody titers greater than 1:50 to the0.6M-DE-urea-GBM antigen. Some of these patients had particularly hightiters of antibody in our assay, while the one control who did react hada relatively low titer of antibody (1:70). Three patients with rapidlyprogressive GN were studied, all of whom were known to be positive forGoodpasture's antibody by radioimmunoassay. One of these patients alsohad antibodies to the GBM derived proteoglycan. Rabbit antisera to humanand bovine GBM reacted in very high titers (greater than 1:1000) to the0.6M-DE-urea-GBM, while preimmune rabbit sera showed no reactivity. Thisdata showed the cross-reactivity of the bovine and human antigens. Insummary, these data demonstrated that patients with GN have antibodiesto bovine GBM derived proteoglycan which are cross-reactive with humanproteoglycan.

In this study, we have examined the humoral reactivity to anionicglomerular proteoglycan antigens derived from both bovine and humanglomeruli. These proteoglycan antigens were isolated by 4M guanidineextraction of whole glomeruli, and further purification onDEAE-Sepharose CL-6B followed by Sepharose CL-4B chromatography. Thematerial isolated was shown to have features characteristic ofproteoglycans. High contents of glucosamine, glucuronic acid, and somegalactosamine were found, in addition to protein. The purified materialhad a high molecular weight as noted by SDS-PAGE: molecular weightheterogeneity was noted. Staining of these gels with Alcian blueconfirmed that the high molecular weight material was the isolatedanionic fraction. Isoelectric focusing confirmed the anionic nature ofthe purified material, yielding a pI of approximately 2.9 to 3.5.Enzymatic and chemical susceptibilities confirmed the presence ofheparan sulfate and either chondroitin sulfate or dermatan sulfateproteoglycans. Purified peak I material contained only glucosamine andno galactosamine, indicating the likelihood that peak I representspurified heparan sulfate proteoglycan. Whether peak II, which containsboth glucosamine and galactosamine, represents a hybrid proteoglycanmolecule, or two proteoglycans which cannot be separated by our methods,will require further investigations.

Immunoblotting studies with the sera of patients with various forms ofGN showed reactivity to the purified broad banded heterogenous highmolecular weight material isolated after Sepharose CL-4B chromatography.Using ELISA, about 50% of patients with APSGN had high titeredantibodies in their serum which reacted with the glomerular proteoglycanantigen. Patients with various histologic forms of chronic GN, includingpatients with CPSGN, also had antibodies to this antigen, although inlower titers. Studies using both human and bovine antigenic preparationsyielded similar results. In addition, rabbit antisera made to bothbovine and human GBM reacted with the bovine glomerular proteoglycan toa similar degree. These studies indicate significant cross-reactivitybetween the human and bovine glomerular proteoglycan, and that thebovine material is useful for the detection of anti-glomerularproteoglycan antibodies in human sera in patients with various forms ofGN.

The antigenic specificity of the immune reaction was furtherinvestigated by ELISA inhibition experiments which revealed the presenceof two immunodeterminants. One antigenic site identified by inhibitionexperiments was heparan sulfate. The finding of immunoreactivity to0.4M-peakI material, which contained no N-acetylgalactosamine,demonstrated the presence of specific immunoreactivity to heparansulfate proteoglycan. Inhibition of immunoreactivity to the glomerularproteoglycan was demonstrated with heparan sulfate. Hyaluronate alsoinhibited the immunoreactivity, but was a less efficient inhibitor.Hyaluronate has a similar repeating disaccharide structure to heparansulfate but is nonsulfated, suggesting that sulfation per se may play arole in the antigenicity of these GAGs.

These inhibition experiments also suggest cross-reactivity betweenheparan sulfate and hyaluronate. Since both GAG's contain a repeatingdisaccharide unit of N-acetylglucosamine and glucuronic acid, and bothcontain 1,4 linkages, either site may contribute to the cross-reactiveantigen. Inhibition of immunoreactivity in patients with APSGN toheparan sulfate proteoglycan was noted with both mammalian andstreptococcal hyaluronate. The streptococcus contains a capsule ofhyaluronate which is identical to mammalian hyaluronate. It isconceivable that these cross-reactions between heparan sulfate and bothmammalian and streptococcal hyaluronate could account for previouslyobserved cross-reactions between streptococcal antigens and glomerularbasement membrane antigens (Markowitz, A. S., et al. (1964) J. Immunol.92:565-567). The monosaccharide N-acetylglucosamine did not inhibit theimmunologic reaction to anysignificant degree, even at 1Mconcentrations. This could be explained by the observations of Kabat(Kabat, E. A., et al. (1971) Inhibition Reactions in ExperimentalImmunochemistry C. C. Thomas, Springfield, Ill. pp. 241-167) that theoptimum binding site of polysaccharide antigens often requires multiplerepeating determinants, with a certain optimum size of 4-6 molecules forthe best fit into the antibody combining site. In summary, theseobservations indicate that antibodies to heparan sulfate of glomerularproteoglycan are found in patients with various forms of GN. Additionalimmunoreactivity to the protein core cannot be ruled out at this time.

The second antigenic site appears to be an immunodeterminant which isrelated to N-acetylgalactosamine. This was shown by inhibitionexperiments employing N-acetylgalactosamine and group C carbohydrate.Greater amounts of these materials were required to demonstrateinhibition on a weight basis than the heparan sulfate site, suggestingthat the N-acetylgalactosamine determinant is a minor one. Galactosaminecontaining proteoglycan always co-migrated with the heparan sulfateproteoglycan, and represented approximately 15% of the total hexosaminein the purified material. Inhibitions with various GAG's containingN-acetylgalactosamine were essentially unremarkable, although in oneexperiment dermatan sulfate demonstrated some inhibition in higherconcentrations. It is possible that the N-acetylgalactosamine siterepresents immunoreactivity to either chondroitin sulfate or dermatansulfate which we have not been able to detect by inhibition, or possiblya galactosamine containing oligosccharide side chain of the protein coreOther investigators (Couchman, J. R., et al. (1984) Nature 307:650-652)have shown that chondroitin sulfate is immunoreactive using monoclorialreagents, and that chondroitin sulfate is found in the glomerulus,primarily in the mesangial regions. This mesangial chondroitin sulfateproteoglycan would be present in our 4M guanidine extract of wholeglomeruli. Thus, we postulate either the presence of two separateproteoglycans in our peak II preparation, or the presence of a hybridmolecule containing two different GAG chains.

The role of charge in the antibody binding to proteoglycan wasinvestigated. ELISA studies of the specificity of this reaction revealedthat the interaction was clearly not due to nonspecific chargeinteractions, since lM NaCl had no effect on antibody binding.Furthermore, neither cationic immune complexes nor anti-DNA antibodiesto anionic DNA were found to account for the observed reactivity. Thefinding of similar immunoreactivity to the 0.4M, 0.5M, and 0.6M NaClmolar eluates of the DEAE-Sepharose CL-6B chromatography furtherpurified by Sepharose CL-4B indicates that the heterogeneous nature ofthe proteoglycan with respect to minor charge differences had no grossdetectable influence on the overall antigenicity of the molecule. Theseresults indicated that charge alone did not account for the observedantibody binding.

In order to further demonstrate that the glomerular proteoglycans wereisolated from whole glomeruli were at least in part derived from theGBM, which is often a primary site of pathology in glomerular disease,conventional detergent procedures for the isolation of GBM wereemployed, followed by urea extraction, and further fractionation onDEAE-Cellulose chromatography. We noted by immunoblotting that antigenicmaterial was being lost using this extraction method. Results in TableII demonstrate that most of the aminosugar containing material,including sulfated GAG representing primarily proteoglycans, are presentin the DNase-lM NaCl and the sodium deoxcholate extract, while little(15%) material is left in the purified basement membrane which isextractable with 4M guanidine. This data further demonstrated the valueof using 4M guanidine extraction of whole glomeruli for the isolation ofglomerular proteoglycans in significantly larger yields. When thepurified anionic fraction of the 8M urea GBM extract was used fortesting in the ELISA, patients with CPSGN, proliferative GN, as well asother types of GN, were found to have antibodies in their serum to thismaterial. However, only one of three patients with RPGN, who were knownto have antibodies to Goodpasture's antigen, had antibodies to theanionic fraction of the 8M urea extract. Since Goodpasture's antigenappears to be a cationic protein (Weislander, J., et al. (1984) Supra),these data indicate that the 8M urea extract of GBM contains multiplecomponents, and that further purification of this material yields apurified anionic fraction of GBM which is antigenically distinct fromGoodpasture's antigen, and is the focus of an immune response in somepatients with various types of GN, including RPGN. Finally, sincesimilar results were obtained with proteoglycans derived from wholeglomeruli and from the isolated GBM, we conclude that immunoreactivityto proteoglycan derived from whole glomeruli represents, at least inpart, antibodies to GBM associated proteoglycan, as well asproteoglycans derived from other regions of the glomerulus.Proteoglycans derived from whole glomeruli appears to yield a betterquantity of antigenic proteoglycan material.

The mechanism which accounts for the development of glomerularproteoglycan autoimmunity is not known. It is possible that afterinflammatory injury, the exposure of hidden proteoglycan antigens to theimmune system, particularly in conjunction with the onset ofcross-reactive immunity incited by a streptococcal infection, couldresult in the onset of active autoimmunity in a genetically appropriatehost. In patients with APSGN, the onset of immunity to this tissueantigen could be a harbinger of chronicity. Indeed, the finding ofmoderate titers of antibody to glomerular proteoglycan antigen inpatients with CPSGN suggests this hypothesis could have some validity. Asimilar mechanism ma be operative in patients with other forms ofchronic GN, and could play a role in the progression of chronic GN inthese patients as well. In addition to the immunologic implications ofour findings, since the glomerular heparan sulfate proteoglycan hasimportant physiologic significance with regard to the filtration barrierfunction of the basement membrane (Cotran, R. S., et al. (1983) NewEngl. J. Med. 309:1050-1052), antibodies to this antigen should alsohave pathophysiologic importance, particularly in regard to proteinuria.

Mammalian antigens in general may well serve as a source of antigen forGN testing.

                  TABLE I                                                         ______________________________________                                        ANALYSIS OF HEXOSAMINES FROM DEAE-                                            SEPHAROSE CL-6B CHROMATOGRAPHY                                                           Micro-          Micro-                                                        moles           moles                                                         hexosa-                                                                              %        hexosa-  %                                                    mine   GLCN     mine     GALN                                      ______________________________________                                        Fall Though                                                                            greater 20       80     0.7    20%                                            than                                                                 0.1 M NaCl elution                                                                         0.3      100      --     --                                      0.2 M NaCl elution                                                                         0.7      60       0.2    40                                      0.3 M NaCl elution                                                                         0.3      60       0.1    40                                      0.4 M NaCl elution                                                                         2.0      73       1.     27                                      0.5 M NaCl elution                                                                         5.7      83       1.     17                                      0.6 M NaCl elution                                                                         2.       65       1.     35                                      0.7*         0.1                                                              0.8*         0.1                                                              ______________________________________                                         *For the 0.7 and 0.8 M eluates 100% of the aminosugar is glucosamine.         Aminosugars, glycosaminoglycans are seen primarily in the 0.4-0.6 M           eluates in FIG. 1                                                             GLCN = glucosamine                                                            GALN = galactosamine                                                     

                  TABLE II                                                        ______________________________________                                        Chemical Composition and Properties of Bovine                                 Glomerular Proteoglycans                                                      ______________________________________                                        Chemical Composition                                                                             Uronic   Glucos-                                                              Acid     amine                                                       Protein  (nmoles/ (nmoles/                                                                             Galactosamine                              Sample    (ug/ml)  ml)      ml)    (nmoles/ml)                                ______________________________________                                        0.4 M - peakI                                                                           1020      630     480    nil                                        0.4 M - peakII                                                                           40      3300     930    210                                        0.5 M - peakI                                                                           200       480     455    nil                                        0.5 M - peakII                                                                          410      4300     1300   300                                        ______________________________________                                        Properties by susceptibility to specific enzymes and chemical                 treatments                                                                    Fraction  Papain   Chondroitinase ABC                                                                           Nitrous Acid                                ______________________________________                                        0.4 M - peakI                                                                           +        -              +                                           0.4 M - peakII                                                                          +        +              +                                           ______________________________________                                         Similar results were obtained with 0.5 M and 0.6 M eluates of the             Sepharose CL4B column.                                                   

                                      TABLE III                                   __________________________________________________________________________    Hexosamine Content of Sequential Extractions of Human Glomeruli                                                 Hexosamine                                                           Total Hexosamine                                                                       in sulfated glycosaminoglycan                 Extraction             GlcN GalN                                                                              GlcN    GalN                                __________________________________________________________________________    I. Whole Human Glomeruli 10.66*                                                                             1.45                                                                              5.76    1.39                                II.                                                                              Sequential Extracts During Isolation of GBM:                               A. DNase-1 M NaCl extract                                                                              0.60 0.07                                                                              0.24    0.06                                B. Sodium Deoxycholate extract                                                                         8.46 1.11                                                                              4.01    1.00                                III.                                                                             4 M guanidine extract of isolated GBM                                                               1.46 0.18                                                                              0.64    0.16                                IV.                                                                              Residue               0.14 0.04                                                                              0.04    trace                               __________________________________________________________________________     *all values are expressed as micromoles per gram of dry weight                **Papain digests were fractionated on DEAEcellulose (DE52) and                glycosaminoglycans were eluted with 2 M HCl                              

                  TABLE IVa                                                       ______________________________________                                        ELISA STUDIES OF 0.4 M - PEAKII ANTIGEN                                       0.4 M - PeakII   A405                                                         Antigen          Control  APSGN                                               Microgram/ml     Sera     Sera                                                ______________________________________                                        10               0.4      2.0                                                 1.0              0.3      1.4                                                 0.1              0.3      0.6                                                 ______________________________________                                         The antigen is titrated from 10 to 0.1 microgram/ml. Sera are from            controls and patients with APSGN.                                        

                  TABLE IVb                                                       ______________________________________                                        ELISA STUDIES OF 0.4 M - PEAKII (10 MICROGRAM/                                ML) (SERA FROM PATIENTS WITH APSGN, CPSGN                                     AND CONTROLS)                                                                          A405                                                                                APSGN (2)  CPSGN (5)                                           Serum  Con-    Patient    Patient                                             dilution                                                                             trol    1       2    1    2    3    4    5                             ______________________________________                                        1:20   0.35    2.0     2.0  0.3  0.3  0.86 0.95 1.1                           1:40   0.37    1.6     2.0  0.25 0.27 0.56 0.60 0.65                          1:80   0.30    0.85    1.71 0.22 0.3  0.38 0.45 0.5                            1:160 0.30    0.47    1.18 0.2  0.3  0.32 0.38 0.4                            1:320 0.20    0.4     0.5  0.18 0.25 0.25 0.3  0.36                          ______________________________________                                    

                  TABLE V                                                         ______________________________________                                                    Titer*                                                            Diagnostic Group                                                                             <20         >20                                                ______________________________________                                        ELISA Studies of 0.4 M - peakII Proteoglycan                                  APSGN // (7)**                                                                              2           5 (148.8 ± 50.3)***                              CPSGN (2)     0          2 (38)                                               Prol. GN (3)  1          2 (38)                                               MGN (2)       2          0 (-)                                                MPGN (1)      0          1 (96)                                               GN-HD (1)     0          1 (28)                                               All GN (16)   5          11 (85.3 ± 28.4)                                  NGRD (2)      2          0                                                    controls (8)  8          0                                                    ELISA Studies of 0.5 M - peakII Proteoglycan                                  APSGN (4)     2           2 (189 ± 48)                                     CPSGN (11)    5          6 (40.3 ± 32.3)                                   Prol. GN (3)  3          0                                                    MPGN (2)      1          1 (40)                                               RPGN (1)      1          0                                                    GN-HD (1)     1          0                                                    All GN (22)   13         9 (73.1 ± 24)                                     NGRD (2)      2          0                                                    controls (13) 12         1 (88)                                               ______________________________________                                         *titers expressed as the reciprocal of the dilution giving a absolute         spectrophotometric reading of 1.0 at 405 nm.                                  **number of subjects                                                          ***represents the mean titer ± standard error for the patients with        titer greater than twenty.                                                    // Abbreviations used in ELISA tables                                         RPGN-- rapidly progressive GN                                                 APSGN-- acute poststreptococcal GN                                            CPSGN-- chronic poststreptococcal GN                                          Prol. GN-- proliferative GN                                                   MGN-- membranous GN                                                           FGS focal glomerular sclerosis                                                MPGN-- membranoproliferative GN                                               NGRD-- nonglomerular renal disease                                            GNHD-- dialysis                                                               GN-- glomerulonephritis, not biopsie                                     

                  TABLE VI                                                        ______________________________________                                        ELISA STUDIES OF 0.4 M - PEAKII                                               (10 MICROGRAM/ML).                                                            A405                                                                          Serum   Rabbit       Anti-Bovine                                                                              Anti-Human                                    Dilution                                                                              Pre-immune   GBM        GBM                                           ______________________________________                                        1:20    0.25, 0.3    1.5        1.3                                           1:40    0.25, 0.3    1.3        1.18                                          1:80    0.15, 0.2    1.1        0.9                                            1:160   0.15, 0.18  0.8        0.7                                            1:320  0.18, 0.2    0.5        0.6                                           ______________________________________                                         ELISA STUDIES OF 0.4 M  PEAKII (10 MICROGRAM/ML). (THE SERA OF PREIMMUNE      RABBITS AND RABBITS IMMUNIZED WITH HUMAN AND BOVINE GBM ARE SHOWN. THE        ANTISERUM MADE TO HUMAN GBM CROSS REACTS WITH THE BOVINE ANTIGEN)        

                  TABLE VII                                                       ______________________________________                                        ELISA INHIBITION STUDIES OF 0.4 M - PEAKII                                    ANTIGEN (10 MICROGRAM/ML). (AN APSGN SERUM                                    WAS INCUBATED WITH INCREASING                                                 CONCENTRATIONS OF NACl                                                        APSGN    PBSA,     PBSA,       PBSA,                                          Serum    0.5%      0.5% Tween  0.5% Tween                                     Dilution Tween     (0.65 M NaCl)                                                                             (1.0 M NaCl)                                   ______________________________________                                        1:20     1.5       1.3         1.3                                            1:40     1.3       1.0         0.9                                            1:80     0.8       0.7         0.6                                             1:160   0.5       0.5         0.42                                            1:320   0.3       0.45        0.40                                           ______________________________________                                    

                  TABLE VIII                                                      ______________________________________                                        ELISA INHIBITION STUDIES OF HUMAN DE-0.6 M                                    ELUATE (10 MICROGRAM/ML). (AN APSGN SERUM                                     (1:40) WAS PRE-INCUBATED WITH VARIOUS                                         PURIFIED GLYCOSAMINOGLYCANS AT VARYING                                        CONCENTRATIONS.)                                                                        A405                                                                          Micrograms/ml                                                                 250    125    62       31   16                                      ______________________________________                                        Chondroitin-4-                                                                            1.87     1.8    1.82   1.7  1.8                                   Sulfate                                                                       Chondroitin-6-                                                                            1.7      1.65   1.65   1.6  1.8                                   Sulfate                                                                       Dermatan Sulfate                                                                          1.5      1.5    1.55   1.6  1.8                                   Heparin     1.5      1.5    1.6    1.4  1.5                                   Bovine Hyaluronate                                                                        1.3      1.4    1.5    1.6  1.8                                   Heparan Sulfate                                                                           0.8      0.9    1.0    1.0  1.4                                   Control (APSGN                                                                            1.7      1.7    1.7    1.7  1.7                                   1:40 Alone)                                                                   ______________________________________                                    

                                      TABLE IX                                    __________________________________________________________________________    ELISA INHIBITION STUDIES OF HUMAN DE-0.6 M ELUATE                             (10 MICROGRAM/ML) (AN APSGN SERUM 1:40 WAS PRE-                               INCUBATED WITH HEPARAN SULFATE GLYCOSAMINO-                                   GLYCAN (HeS) BOVINE HYALURONATE [HYA (BOV)] AND                               STREPTOCOCCAL HYALURONATE [HYA (STR)] AT                                      VARYING CONCENTRATIONS.                                                              A405                                                                          mg/ml                                                                         10 5  2.5                                                                              1.5                                                                              0.62                                                                             0.325                                                                            0.162                                                                            0.082                                                                            0.041                                                                            0.022                                       __________________________________________________________________________    APSGN Sera                                                                           1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                         (1:40)                                                                        +HeS                  0.75                                                                             0.8                                                                              0.85                                                                             1.1                                                                              1.5                                         +Hya (Bov)                                                                              0.8                                                                              0.85                                                                             0.9                                                                              1.1                                                                              1.2                                                     +Hya (Str)                                                                           0.5                                                                              0.5                                                                              0.55                                                                             0.6                                                                              0.75                                                       __________________________________________________________________________

                  TABLE X                                                         ______________________________________                                        ELISA INHIBITION STUDIES OF 0.4 M - PEAKII                                    ANTIGEN (10 MICROGRAM PER ML) [AN APSGN                                       SERUM (1:40) WAS PREINCUBATED WITH VARIOUS                                    INHIBITORS: DERMATAN SULFATE (DeS), N-ACETYL                                  GLUCOSAMINE (N-GLU N), N-ACETYL GALACTOS-                                     AMINE (N-GAL N), STREPTOCOCCAL HYALURON-                                      ATE (STR. HYA.) AND HEPARAN SULFATE (HeS)]                                                A405                                                                          APSGN Serum Dilution                                                          1:40     1.80    1:160                                            ______________________________________                                        Serum         1.8        1.3     0.8                                          Serum + DeS (0.25                                                                           1.5        1.1     0.75                                         mg/ml)                                                                        Serum + N-glu N                                                                             1.25       0.9     0.6                                          (1 M)                                                                         Serum + N-gal N                                                                             1.05       0.75    0.4                                          (1 M)                                                                         Serum + Str. Hya.                                                                           0.8        0.5     0.4                                          (5 mg/ml)                                                                     Serum + HeS (0.25                                                                           0.4        0.38    0.35                                         mg/ml)                                                                        Serum + N-gal N                                                                             0.3        0.3     0.3                                          (1.0 M) and Str.                                                              Hya. (5 mg/ml)                                                                ______________________________________                                    

                  TABLE XI                                                        ______________________________________                                        Inhibition of ELISA Reactivity to Human DE-0.6 M Antigen                       Inhibitor              Percent Inhibition                                    ______________________________________                                        Heparan sulfate GAG (0.1 mg/ml)                                                                       51.3%                                                 Streptococcal Hyaluronate (5 mg/ml)                                                                   68%                                                   Human umbilical cord hyaluronate (5 mg/ml)                                                            48%                                                   Group C streptococcal carbohydrate                                                                    56%                                                   (5 mg/ml)                                                                     Group A streptococcal carbohydrate                                                                    9%                                                    (5 mg/ml)                                                                     Group A variant strep. carbohydrate                                                                   9%                                                    (5 mg/ml)                                                                     ______________________________________                                         The serum from a patient with APSGN at a 1:40 dilution was used for these     studies.                                                                 

                  TABLE XII                                                       ______________________________________                                        ELISA Studies of Bovine 0.6 M-DE-urea GBM Antigen*                                        Serum Titer                                                       Diagnostic Group                                                                            <50        50-100  >100                                         ______________________________________                                        RPGN (3)      2          0       1                                            Prol. GN (3)  0          1       2                                            APSGN (2)     0          0       2                                            MGN (4)       3          1       0                                            FGS (2)       1          1       0                                            MPGN (2)      1          1       0                                            GN-HD (6)     3          1       2                                            GN (6)        4          0       2                                            All GN (28)   14         5       9                                            controls (8)  7          1       0                                            ______________________________________                                         *Results are expressed as in Table IV.                                        Abbreviations as shown on Table V.                                       

What is claimed is:
 1. A kit for the diagnosis of acute or chronic humanpost-streptococcal glomerulonephritis which comprises purified bovine orhuman anionic, solubilizable glomerular glucosamine or galactosaminecontaining proteoglycan antigens of about 200,000 molecular weightwherein the ratio of glucosamine:galactosamine is approximately 4.5:1and said antigen is capable of immunologically reacting withhuman IgGand IgM antibodies in human sera in patients with post-streptococcalglomerulonephritis.